The invention relates generally to machine slideways for supporting machine elements on relatively movable slides. In machine slideway art, particularly in those used in machine tools where the slideways and their associated components are relatively heavy (such as grinding wheelheads), it has long been a problem to create a machine slideway which is capable of relatively small, precise steps of movement in normal operation, which steps may be necessitated by tool wear or grinding wheel reduction as in a centerless grinder, and it is desirable to compensate the grinding wheel (or work) support slide to maintain sizing of the workpiece. The phenomenon of friction is well-known to machine designers, and, in particular, a related phenomenon known as "stick-slip" is frequently encountered when the weight of the components assumes a large magnitude, as in a centerless grinder regulating wheel support slide. The coefficient of friction is generally thought to be a relative term created by the materials of the components bearing on one another. While the phenomenon of stick-slip is not totally understood, it is thought that a certain attraction may develop between two members bearing on one another, and, on a microscopic scale, the very minute craggy surface textures may become mechanically intermeshed with one another to cause a drag at such time as may become necessary to relatively move the components.
Several prior art slideway designs have been attempted to accomplish a smooth relative movement of one slide to another, such as: (a) plain slideways, wherein both relatively moved components are finely scraped or ground, to try to divide lubrication oil over the whole sliding surface; (b) a serrated moving member of a slidway moving on a finely scraped mating member, attempting to still further lubricate the interface surface with a lubricant; (c) ball track or needle roller supports, wherein the antifriction elements are mounted in a cage and roll on hardened strips mounted to mating slideways; (d) plain slideway and cooperating antislip material such as the well-known fluorocarbon plastic inserts; (e) hydrostatic pockets provided to lift a slide on an oil film against a mating part. Many disadvantages are inherent in the prior art slideway designs. For example, the plain slideways have a high friction potential and pickup between the interface materials may be due to any lack of lubricant--in combination with vibratory loads. The serrated slides (especially where cast iron is used against cast iron) resulted in a great improvement over the lubricated plain slides, however, one cannot be insured that lubricant will be totally spread over every position of the slide on its mating part. Therefore, stick-slip and a substantial amount of friction are usually present and thus, it is difficult to maintain good repeatability of compensation movements with this type slide. The antifriction roller assemblies are disadavantages in the fact that pure rolling is not generally obtainable, but a combination of sliding and rolling may exist, wherein the rollers and their cages tend to migrate to end of the slide or the other. Further, the rollers or balls may tend to brinell into the support track surface, thus interfering further with the preload and smooth rolling of the assembly. The use of antifriction way material very definitely results in no-pickup under vibratory loads and small stick-slip problems. However, wear is great problem, resulting in replacement of machine elements to insure sizing capabilities of the machine which creates an overall expensive assembly. The hydrostatic pocket method of supporting slideways gives an extremely low friction slide assembly, with no stick-slip problems, but this type of antifriction slideway is disadvantageous for precision machines such as grinders, because of its low damping capacity and lower static stiffnesses, which will result in a lesser ability to dampen any machine vibrations. Further, it is a great problem to collect oil and drain it away from the slide assembly and keep the oil free of contaminents. Sealing of the slideway is difficult in the presence of chips and swarf, etc.
Applicant has obviated the difficulties inherent in these prior art slideways.